The illumination of the manuscript consists of a large initial N on page two of the manuscript and several other minor initials. The N is as large as nine lines of the main text. It is written in black ink and decorated by whorl and cross patterns and pelta motifs. There are touches of green and orange. The cross bar is formed, in part, by two fish bent to form an S curve. The form of the N is comparable to the initial INI monogram of the opening illumination of the Gospel of Mark found in a fragmentary Gospel Book from Durham Cathedral.
On page two there is an inscription connecting the manuscript to Atalanus, who was St. Columbanus's successor as abbot of the monastery at Bobbio. Atalanus died in 622. If this inscription is accepted as authentic, then this manuscript was produced before 622, making its initial N one of the earliest Insular style intials, preceding even the Cathach of St. Columba.